Search Images Maps Play YouTube News Gmail Drive More »
Sign in
Screen reader users: click this link for accessible mode. Accessible mode has the same essential features but works better with your reader.

Patents

  1. Advanced Patent Search
Publication numberUS4674330 A
Publication typeGrant
Application numberUS 06/838,427
Publication dateJun 23, 1987
Filing dateMar 7, 1986
Priority dateJan 24, 1984
Fee statusLapsed
Publication number06838427, 838427, US 4674330 A, US 4674330A, US-A-4674330, US4674330 A, US4674330A
InventorsMalcolm I. Ellis
Original AssigneeMie Medical Research Limited
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Apparatus for measurement of grip and pinch strength
US 4674330 A
Abstract
Apparatus (1') for measurement of both the grip strength of a person's hand and pinch strength of two digits of the hand comprises two parallel grip handles (2', 3') extending at right angles from a third member (4'). Handle (3') is rigidly fixed to third member (4') and has two pairs of strain gauges mounted thereon to measure the force applied to the handles irrespective of where that force is applied. Handle (2') is adjustable with respect to handle (3') to alter the distance between the two handles, and the ends of the handles terminate in flat portions (6', 7') to be used for measurement of pinch strength.
Images(10)
Previous page
Next page
Claims(7)
I claim:
1. Apparatus for measuring grip strength of a person's hand and pinch strength of two digits of the hand, the apparatus comprising grip handles which are in the form of two substantially parallel elongate members extending substantially at right angles from and attached to a third member, the first of said handles being rigidly fixed to one end of said third member, and the second of said handles being slidably accommodated within said third member so that the distance between the two handles may be altered to adjust the apparatus between a first condition in which it is suitable for measurement of grip strength and a second condition in which it is suitable for measurement of pinch strength, means to lock said second handle in a predetermined position, at least two strain gauges mounted on one or both of the handles to provide an electrical signal indicative of a force applied to the handles, said signal being substantially independent of the point of application of the force, and an electrical connection to a processing and display unit for receiving said signal and converting it to a form suitable for display.
2. Apparatus according to claim 1 in which four strain gauges are mounted in two pairs on the first handle, both members of each pair being connected together in parallel to increase the sensitivity of the apparatus, and each pair being mounted a fixed distance apart along the longitudinal axis of the handle.
3. Apparatus according to claim 2 in which the two pairs of strain gauges are connected into a bridge network, and the processing means calculates the total force applied from the difference between the signals on the two pairs of strain gauges.
4. Apparatus according to claim 2 in which the handles are made of steel.
5. Apparatus according to claim 1 in which each handle is covered with foam padding and a non-slip material covering on the outside of the padding.
6. Apparatus according to claim 5 in which, at the end of each handle furthest away from the third member there is no padding or covering, each handle terminating in a flat bare portion suitable for placing a thumb and finger on for measuring pinch strength.
7. Apparatus according to claim 1 in which the handles are made of aluminium.
Description

This is a continuation-in-part of co-pending application Ser. No. 693,178, filed on Jan. 22, 1985, now abandoned.

The present invention relates to apparatus for measuring the grip strength of a person's hand, and also the pinch strength between two digits of the hand.

It is useful for doctors to be able to objectively monitor the progress of patients who have suffered hand injury, either through accidents or debilitating diseases such as arthritis, or who have undergone hand surgery, for example, to replace one of the finger joints with a prosthetic joint.

Several devices exist for measuring grip strength of the hand, but these suffer from several disadvantages.

One such device is described in a paper by Petrofsky et al, "Proceedings of the IEEE 1981 National Aerospace and Electronics Conference, Dayton, Ohio, USA (19th to 21st May 1981)".

This device is designed to measure the grip strength of a pilot's hand, specifically for the purpose of examining isometric performance characterstics. It does not include any means for also measuring the pinch strength between two digits, and would not in any case be suitable for use by a person having fixed flexion deformities resulting from say arthritis, which prevent the person from unclenching their hand completely.

According to the present invention there is provided apparatus for measuring grip strength of a person's hand and pinch strength of two digits of the hand, the apparatus comprising grip handles which are in the form of two substantially parallel elongate members extending substantially at right angles from and attached to a third member, the first of said handles being rigidly fixed to one end of said third member, and the second of said handles being slidably accommodated within said third member so that the distance between the two handles may be altered to adjust the apparatus between a first condition in which it is suitable for measurement of grip strength and a second condition in which it is suitable for measurement of pinch strength, means to lock said second handle in a predetermined position, at least two strain gauges mounted on one or both of the handles to provide an electrical signal indicative of a force applied to the handles, said signal being substantially independent of the point of application of the force, and an electrical connection to a processing and display unit for receiving said signal and converting it to a form suitable for display.

Thus, with the apparatus of the present invention, both the grip strength of a person's hand and the pinch strength of his finger and thumb may be measured using the same piece of apparatus, simply by adjusting the distance between the two handles.

This adjustability also means that if a person has fixed flexion deforminities and is thus unable to clench his hand fully, the distance between the handles can be reduced by sliding the second handle nearer to the first and locking it in position to suit the degree to which the person can unclench his hand.

Preferably the apparatus has four strain gauges mounted in two pairs on the first handle, both members of each pair being connected together in parallel to increase the sensitivity of the apparatus, and each pair being mounted a fixed distance apart along the longitudinal axis of the handle.

Preferably the two pairs of strain gauges are connected into a bridge network, and the processing means calculates the total force applied from the difference between the signals on the two pairs of strain gauges.

This particular arrangement of strain gauges ensures that, within certain limits, wherever the person places his hand or fingers on the handles, the reading obtained from the apparatus will be the same for a given grip or pinch strength. This is particularly desirable when monitoring one person over a long period of time, or when comparing the grip or pinch strength of an arthritic hand with that of a normal one.

Preferably each handle is covered with foam padding and a non-slip material covering on the outside of the padding, such that the part of the handle which is in contact with the person's palm and fingers when used for grip strength measurement, is semi-circular in cross-section and so comfortable to the hand.

Preferably at the end of each handle, furthest away from the third member, there is no padding or covering, and each handle terminates in a flat bare portion suitable for placing a thumb and finger on for measuring pinch strength.

The apparatus may be connected to a simple processor and display means which includes a sample and hold circuit to indicate the highest grip or pinch force in Newton. It may alternatively be connected to a computer which can analyse other aspects of the person's grip or pinch strength, such as grip rate, fatigue rate, fatigue release rate, etc.

The handles may be made of aluminum for persons likely to have a low grip strength of, say, less than 400 Newtons, or alternatively steel handles may be used for use in sports or gymnasium measurements.

Several examples of apparatus in accordance with the invention will now be described with reference to the accompanying drawings, in which

FIG. 1 is a schematic view of a first example of the apparatus;

FIG. 2 is a schematic view through the grip measuring apparatus of FIG. 1;

FIG. 3 is a circuit diagram of the processor means;

FIG. 4 is a perspective view of the pinch meter of the first example of the appratus;

FIG. 5 is a section through the pinch meter of FIG. 4;

FIG. 6 is a schematic view of a second example of apparatus;

FIG. 7 is a view of the circuit arrangement used in the processor of the apparatus of FIG. 6;

FIG. 8 is a perspective view of the apparatus of the present invention;

FIG. 9 is a side view, showing internal detail of the apparatus of the present invention;

FIG. 10 is a top plan view in the direction A of the apparatus shown in FIGS. 8 and 9, showing details of the second handle;

FIG. 11 is a plan view in the direction B of the apparatus shown in FIGS. 8, 9 and 10;

FIG. 12 shows the apparatus of the present invention being used for the measurement of grip strength;

FIG. 13 shows the apparatus of the present invention being used for the measurement of pinch strength;

FIG. 14 shows displayed force plotted as a function of distance of point of application of force from the tip of the handle, for two different constant forces and aluminium handles;

FIG. 15 shows displayed force plotted as a function of distance of point of application of force from the tip of the handle, for two different constance forces and steel handles; and,

FIG. 16 is a circuit diagram of a processor and display unit for use with the apparatus of the present invention.

A first example of apparatus in accordance with the invention comprises (see FIG. 1) two parallel grip handles (1, 1a) rotatably mounted on a U-shaped grip member 2. The ends of the U-shape are connected to a perpendicular H-shaped member 3. The grip handles (1, 1a) are rotatably mounted so that any turning forces applied by the grip are eliminated. Members 2 and 3 are made of a metallic material. In the centre bar of the H-shaped member 3 are two strain gauges 4 on one side of the metal and two strain gauges 5 on the opposite side of the metal. When force is applied on the grip handles 1 and 1a force is applied through the two walls of the U-shaped member 2 to the strain gauges 4 to give an electrical signal indicative of the strain applied at this point.

For a force F applied anywhere along the handles 1 or 1a which will always be distance d horizontally from the strain gauges 5 and 4. The force F applied to the member 1 will be proportional to F×d. As d is constant the strain measured by the strain gauges 4 and 5 will be directly proportional to F.

The two sets of strain gauges at 5 are required to correct the temperature which has an effect on the readings of the strain gauges. Each strain gauge is a transducer which has a resistance which varies according to the strain applied to the transducer.

The signal from the strain gauge are fed to the processor unit 6 shown in detail in FIG. 3. The processor includes a power supply circuit 7 which provides three separate supplies. A first supply 8 supplies the pinch amplification circuit 9 and the second supply 10 supplies the grip amplification circuit 11 and the third supply 12 supplies the display circuits 13. The pinch amplification circuit 9 and the grip amplification circuit 11 comprise a strain bridge 14 which is a Wheatstone bridge of the transducers forming the strain gauges (4, 5) and amplifiers to amplify the resultant signals. The power supplies 8 and 10 are on constantly so that the transducers forming the strain gauges are always on. This is advantageous since the transducers require to be warmed up and so there is no warming up period required. A switch 15 switches the signals according to whether the pinch of the digits of the hand is to be measured or whether the grip of the hand is to be measured. A logic circuit 16 is used to store the value of the signal fed through switch 15. Since logic gates 17 are used the signal can be stored for up to 20 seconds which is much longer than would be possible if capacitors were used. A sample and hold circuit 18 tests the signal to find whether it is higher than that stored in the logic gates 17. If it is the new value replaces the value in the logic circuit 16. The display may be used on a logic circuit 16. The display may be also used on a normal mode which just displays the instantaneous value coming through switch 15.

The pinch meter is shown schematically in FIGS. 4 and 5. The meter 19 comprises a bifurcated member 20 with two parallel members joined together at one end 21. Strain gauges 22 are situated at end 21 to measure the strain produced by movement of members 20, a plastic guard 23 is placed over the bifurcated member 20 to limit the surfaces 24 which can be used by the operator to pinch the members 20 together. These readings are then fed to the pinch amplification circuit 9 of the processor unit.

A second example of the apparatus obviates the requirement for a pinch meter 19 and comprises two substantially parallel handles 25 connected together at one end 26. Each member 25 has two transducers or strain gauges 27 near end 26. For a force applied F at a distance d1 from first transducer R1, and d2 from the second transducer R2, the difference between the two signals of the transducers R1 and R2 will be F×d1 -F×d2 which will equal F×X where X is the distance between the two transducers which is constant. This means that for a given force applied the same electrical signal will be produced by the transducers wherever the force is applied.

This can be conveniently achieved by producing a Wheatstone bridge of the outputs of the transducers R1, R2, R3 and R4, to provide an electrical signal indicative of the force applied on the two members 25.

Referring to FIGS. 8, 9, 10 and 11 of the accompanying drawings, apparatus according to the present invention comprises two handles 2', 3' in the form of elongate members 8', 9'. The elongate members 8', 9' are attached to and extend at right angles from a third, U-shaped member 4'.

One of the handles, 3', is rigidly fixed at end 4A' of the U-shaped member 4', and the other handle, 2', is slidably secured within the U-shaped member 4' and includes a locking knob 5' which is used to lock the handle 2' into a predetermined position relative to the handle 3'. The U-shaped member 4' has a slot 10' within which the handle 2' can slide.

Each handle comprises a metal body 13', surrounded by foam padding 11' and a plastic non-slip cover 12'. The padding is such that the surface of the handles in contact with the person's palm and fingers is semi-circular in shape, and so is comfortable to the hand.

Two pairs of strain gauges 14', 15' and 16', 17' are mounted on the inside of metal body 13'. Gauges 14' and 15' are wired in parallel, as are gauges 16' and 17', and the two pairs are connected into a bridge network located in the processing unit. Pair 16', 17' is offset from pair 14', 15' by a distance X along the longitudinal axis of the handle 3'. The use of two pairs of strain gauges in this way increases the sensitivity of the apparatus.

Each handle 2', 3' has at its tip a flat, bare metal portion 6', 7' so that the same apparatus may be used for both the measurement of pinch strength and grip strength, by adjusting the distance between the handles 2', 3'.

Referring now to FIG. 12, when the apparatus is to be used for measurement of grip strength, the knob 5' is released, and the handle 2' is slid to a suitable position to suit the person's hand, the knob 5' is then tightened, and the person places his thumb around the handle 3' and all his fingers around handle 2' and squeezes as hard as he can.

Referring to FIG. 13, to adjust the apparatus for measuring pinch strength, the knob 5' is released, the handle 2' is slid down unti it is close to handle 3' the person places a finger under portion 7' and a thumb on top of portion 6' and pinches the two together as hard as he can.

Referring now to FIG. 16, the processing means to which the apparatus is connected measures the difference between the signals produced at each pair of strain gauges as measured by a bridge network 20'. This difference, which is indicative of the force applied regardless of the point of application of the force, is amplified and then fed to sample and hold circuitry 21' and thereafter to a display unit 22'. The sample and hold circuitry stores the highest difference measured, so that a person may have several attempts at using the apparatus, and only the highest force will be displayed.

Since it is the difference between the signals at the two pairs of strain gauges which is measured, the reading displayed is independent of the point of application of the force.

This is substantiated by results of tests on two different types of metal, using standard weights of 10 Kg and 20 Kg applied at different points along the handles, instead of a person's grip.

FIG. 14 shows the results for aluminium handles, and it can be seen from this graph that there is very little variation for each weight up to a distance of 16 cm from the tip of the handle.

Similarly, FIG. 15 shows the results of the same test carried out on steel handls, and this also shows very little variation between different points of application of the force, up to 17 cm from the tip of the handle in the case of 10 Kg, and 16 cm in the case of 20 Kg.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US3031152 *Apr 28, 1958Apr 24, 1962Dusenbery Co JohnImproved apparatus for measuring, indicating, and controlling web tension
US3670573 *Nov 18, 1970Jun 20, 1972Us Air ForceApparatus for measuring thumb and finger force
US4501148 *Jan 5, 1982Feb 26, 1985Nicholas James AManual muscle tester
Non-Patent Citations
Reference
1J. S. Petrofsky, "Digital Controlled Handgrip for Isometric Performance Studies", N.A.E. Conf., Proceedings IEEE, May 1981, pp. 574-580.
2 *J. S. Petrofsky, Digital Controlled Handgrip for Isometric Performance Studies , N.A.E. Conf., Proceedings IEEE, May 1981, pp. 574 580.
3R. A. Dickson et al., "A Device for Measuring the Force of the Digits of the Hand", Bio-Medical Engineering, vol. 7, No. 6, Jul. 1972, pp. 270-273.
4 *R. A. Dickson et al., A Device for Measuring the Force of the Digits of the Hand , Bio Medical Engineering, vol. 7, No. 6, Jul. 1972, pp. 270 273.
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US4890495 *Sep 16, 1988Jan 2, 1990Slane Stephen MDevice for determining the push/pull capabilities of a human subject
US5125270 *Sep 25, 1990Jun 30, 1992N. K. Biotechnical Engineering CompanyLoad sensor for a human hand
US5157970 *Oct 17, 1990Oct 27, 1992Lewis Jr Royce CGrasp analysis method
US5170663 *Oct 3, 1990Dec 15, 1992N. K. Biotechnical Engineering CompanyGrip sensor
US5299457 *Jul 13, 1992Apr 5, 1994Donald PangPrecision grip meter
US5317916 *Aug 25, 1992Jun 7, 1994N.K. Biotechnical Engineering CompanyDigit grip sensor
US5899837 *Apr 2, 1998May 4, 1999Lih Harng Industrial Co., Ltd.Resiliently compressible exercise device
US6029528 *Aug 17, 1998Feb 29, 2000Tiffany And CompanyEarring force tester
US6050961 *Nov 13, 1998Apr 18, 2000Arnold; Robert J.Oromotor dynamometer
US6086518 *Apr 28, 1997Jul 11, 2000Aerovironment, Inc.Squeezable exerciser
US6944914Apr 23, 2003Sep 20, 2005Tillim Stephen LHandle and forceps/tweezers and method and apparatus for designing the like
US6948365 *Sep 6, 2002Sep 27, 2005K.S. Italia S.A.S. Di Ambrosone Mario & Co.Dynamometer and related assessment method
US6988295Oct 24, 2002Jan 24, 2006Tillim Stephen LHandle/grip and method for designing the like
US7010835Oct 24, 2003Mar 14, 2006Tillim Stephen LParallel handle system and method for designing a parallel handle system
US7506409Aug 16, 2005Mar 24, 2009Tillim Stephen LHandle/grip and method for designing the like
US8601869Nov 29, 2011Dec 10, 2013Mark Carl MillerMulti-functional hand strength assessment device
US20020132655 *Mar 7, 2002Sep 19, 2002Mercer Richard D.Electronic kinesiology game device
US20030074766 *Oct 24, 2002Apr 24, 2003Tillim Stephen L.Handle/grip and method for designing the like
US20040078935 *Apr 23, 2003Apr 29, 2004Tillim Stephen L.Handle and forceps/tweezers and method and apparatus for designing the like
US20040088827 *Oct 24, 2003May 13, 2004Tillim Stephen L.Parallel handle system and method for designing a parallel handle system
US20040177686 *Mar 25, 2004Sep 16, 2004Johansson Roland SixtenApparatus for evaluating manual dexterity
US20040199205 *Apr 22, 2004Oct 7, 2004Tillim Stephen L.Handle for forceps/tweezers and method and apparatus for designing the like
US20050061072 *Sep 6, 2002Mar 24, 2005Mario AmbrosoneDynamometer and related assessment method
US20050070824 *Sep 29, 2003Mar 31, 2005Edward RhadResponse testing for conscious sedation using finger movement response assembly
US20050267519 *Jul 20, 2005Dec 1, 2005Tillim Stephen LHandle for forceps/tweezers and method and apparatus for designing the like
US20050278897 *Aug 15, 2005Dec 22, 2005Tillim Stephen LHandle/grip and method for designing the like
US20060123651 *Jan 5, 2006Jun 15, 2006Tillim Stephen LParallel handle system and method for designing a parallel handle system
US20060137144 *Feb 24, 2006Jun 29, 2006Tillim Stephen LHandle/grip and method for designing the like
US20100011541 *Jan 21, 2010Tillim Stephen LHandle and forceps/tweezers and method and apparatus for designing the like
US20100228156 *Sep 9, 2010Valero-Cuevas Francisco JDexterity device
DE10196092B3 *Apr 17, 2001Dec 8, 2011Makoto NakaoMuskeldruckmessgerät zum Messen des von einem Körperteil innerhalb des Mundbereichs ausgeübten Druckes sowie ein Adapter für ein solches Muskeldruckmessgerät
DE102010014895B4 *Apr 14, 2010Feb 13, 2014Deutsches Zentrum für Luft- und Raumfahrt e.V.Verfahren und Messsystem zur Messung der Steifigkeit von Körperteilen
EP2218401A1 *Feb 16, 2009Aug 18, 2010Francisco Valero-CuevasDexterity device
WO1998048698A1 *Oct 27, 1997Nov 5, 1998Aerovironment, Inc.Squeezable exerciser
WO2014041315A1Sep 13, 2013Mar 20, 2014Institut De MyologieDevice for measuring the pinch force between a person's thumb and index finger
Classifications
U.S. Classification73/379.03
International ClassificationG01L1/22, G01L5/00, A61B5/22
Cooperative ClassificationG01L1/225, A61B5/224, A61B5/225
European ClassificationG01L1/22C, A61B5/22D, A61B5/22D2
Legal Events
DateCodeEventDescription
Dec 14, 1990FPAYFee payment
Year of fee payment: 4
Jan 31, 1995REMIMaintenance fee reminder mailed
Jun 25, 1995LAPSLapse for failure to pay maintenance fees
Sep 5, 1995FPExpired due to failure to pay maintenance fee
Effective date: 19950628